Planning a tunnel full of LEDs

I’m working on building a tunnel full of LEDs for Nowhere festival in Spain. After my LED wall for Decompression, I wanted to make a bigger project for Nowhere. The idea for a tunnel came from this awesome project, which my friend Bryan found.

I’m not sure mine will be quite as professional looking, but I do plan to make it interactive!

I’ve been messing about with a bunch of prototypes, using the LEDs in the wall to figure some stuff out, which I’ll write about in other posts. Meanwhile though, I’ve been waiting to hear back from the Nowhere art funding team and, on Wednesday (after a few weeks of nail biting and stress dreams) I found out I got an art grant! The budget is tight so there’s a lot of places to try and trim back, but I’m confident that, along with my own contribution as well, it’s enough to make something really really awesome.

I was holding off working out exact numbers for things like number of leds/metre, number of metres, size of tunnel etc, until I heard about funding. Now I have a budget to work to, I’ve started spec’ing up the specs 🙂

The Specs

First I drew some really loose sketches of how I see the tunnel looking, so I had something to work to.

Another thing I started thinking about is how the LED strips will be wired up. I plan to use PixelPushers to drive the LEDs. The PixelPusher can run 8 strips of 240 LEDs each.

Aww crap

Fun fact! There is a number wrong in the pictures above! I wrote down that the PixelPusher could run 480 LEDs per strip (it’s actually 240 per strip) and then I spent an entire day basing calculations on that figure, meaning that a lot of stuff was out by a factor of 2! Nooooo. I only realised while writing this up. I’ve corrected all the following figures in this blog post,if you look closely you might see the eraser marks. I’m not sure what the lesson is there… using pencil was a good choice?

Anywho, onwards.

I started thinking about how many strips to include, by writing out my thought process like this:

(TIL I leave letters out of words when writing and thinking at the same time.)

Here I started to define some language for myself. Most LED drivers talk about the number of Strips they can run. At 30LED/m, a Strip would be 8 metres, which is too long to stretch across the tunnel. I started to use the word “Lines” to talk about how many lines of LEDs would go in the tunnel. If a “Line” is 4m long, then each “Strip” of 30LED/m can have two Lines. The little diagram in the bottom right hand corner shows loosely how I would wire this (the “nope!” is where I’ve erased the mistake from when I spent a glorious day thinking pixelpushers had double the capacity).

There’s also some little notes to myself. For example, I captured that, if there are fewer lines across the tunnel, there could also be some lines going down the length of the tunnel.

Later, I started referring to the lines going across the tunnel as Parallel Lines, and the lengthways ones as Lateral Lines. If this doesn’t make sense, scroll down to the drawing in blue, where they’re labelled. I think it’s really helpful to define my own language for things like this. It helps avoid having to keep saying things like “the ones that go across, no across like sideways” or whatever, if things are defined.

Having calculated how many lines and strips I could have and what kind of “gaps” I would have between lines for different amounts of 30/m strips, I then worked out these same calculations for 60/m strips.

I didn’t write everything out quite so detailed this time. I had already done the thinking, it’s just another set of sums for a different number of LEDs/meter.

Costs!

I previously bought LED strips from a seller on AliExpress and was very happy with them, so I will be purchasing from them again.

These prices include shipping and are converted from dollars, which is why they don’t multiply out exactly (as if anyone would check). I worked out prices to buy enough LEDs to max out 1, 2, and 3 PixelPushers. Today, when correcting the numbers, I added calculations for 4 PixelPushers.

No matter the LEDs per meter, the number of LEDs for a PixelPusher is the same. 1 PixelPusher always runs 1920 LEDs. The difference will be the layout, I can go for more lines, with the lights spread out further, or fewer lines with the lights closer together.

60LED/m strips come in reels of 4 meters, which would be nice since that’s the length of lines I’m fairly set on. 30LED/m strips come in reels of 5meters, which means I’d have to cut off the extra meter and solder them together (and heatshrink the connections). More work = Butts.

Power!

I guess perhaps I could have done all of this in spreadsheets, but I’m not sure. I found that writing things out on paper really helped the thought process, especially in the earlier stages, when I could jot sums down in sentence form. Don’t worry though, we’re approaching the end of the pages of sums.

Placement!

Having worked out the power and cost calculations, I thought more about layout.

Partly because of my accidentally doubling the capacity of the PixelPushers, I was dealing with huge numbers of LEDs so I decided to think about extending the length of the tunnel from 6m to 7.5m. I really want the tunnel to feel quite immersive, and I think making it longer will help (that’s what she said).

For each of the total lengths of LEDs I’d come to, I worked out a potential layout. I disregarded the idea of 32m of LEDs, its just not enough! These calcs are based on a 7.5mx3m tunnel, where the lights cover around 7m of the length, so there is a little gap inside each end.

OKAY.

That is all the pages of sums!

Here’s a drawing of what it might kinda sorta look like!

7m long lateral lines are actually going to be kind of a pain in the butt to wire up, because it doesn’t fit nicely into the max strip capacity, but these calculations are a good start.

That drawing started to give me an idea of what things might look like, what the scale would be and so on, but I don’t want to have to do a completely new drawing and measure out the gaps between lines and draw all those curves for each different layout, so I decided to make a 3D model.

3D!!!!!

I don’t really know what I’m doing with Cinema4D but I watched a few tutorials and managed to cobble this together. This version is around 128m of 30LED/m strips, using 2 Pixel Pushers (3840 LEDs), there are 5 lateral strips and 23 parallel strips. I added some colour fading animation to the lights also! Hurray! This took 40 mins to render, anyone know if that sounds right? It seems slow but, as mentioned, I have no idea what I’m doing.

And finally…

So after all that, I still haven’t decided what numbers to go with! I think my real options are:

I guess my concern with the 30led/metre strips is that I’ve over represented the size of the light in the render video, the lights will actually look further apart than that. In the Porta Estelar video, those look like 60/m strips, or even 72/m, and the effect is a lot more continuous, but also, it’s super crazy bright, I dont want to blind people, I want it to be nice! Maybe it’d be better to spend less on LEDs and consider an option for diffusing them!?